Training a large number of laboratory mice using running wheels and analyzing running behavior by use of a computer-assisted system.

A great many studies in the literature describe the variety of ways to provide physical training to small laboratory animals. Forced running on a treadmill or swimming training require considerable effort from the researcher, but permit the investigator to control the amount of exercise. Another option is to provide animals with access to running wheels, which they can voluntarily operate. Wheels can be used to investigate the running behavior of the animals. Wheel motion usually has been detected with magnets and microswitches and has been recorded using strip chart recorders or electromechanical counters. Computers also have been used in recording, but the measured parameters usually have been able to define only the total distance run in a fixed period. We designed a system, using running wheels, that can be used for long periods, up to years, for training a large number of laboratory mice simultaneously (maximal n = 96). The running parameters estimated by our system include running distance, speed, and time. Cumulative estimates of the running parameters can be produced for any period, as short as 1 sec. It is also easy to perform statistical analyses on the data. Using the system, we investigated the running behavior of 21 young C57BL/6 male mice. After the fast growth period, until 8 weeks of age, the mice ran 4 to 5 km/day at an average speed of 23 m/min, and spent 3 h running each day. This took place during the hours of darkness.